1. Field of the Invention
The present invention relates to method and apparatus for detecting a position of an object present in a surrounding detection zone of an automotive vehicle.
2. Description of the Related Art
A U.S. Pat. No. 5,767,793 issued on Jun. 16, 1998 and a Japanese Patent Application First Publication No. Heisei 11-304910 published on Nov. 5, 1999 exemplify previously proposed object detecting apparatuses. In these previously proposed object detecting apparatuses, a plurality of ultrasonic sensors are disposed with directions of detection beams deviated, a part of detection ranges of the respective sensors is overlapped to form a plurality of detection ranges, and a rough position of the object is detected according to a detection pattern of the whole sensors.
Such a radar having a detection beam with a spreading angle as the ultrasonic sensor described above can detect only a distance therefrom to a nearest point of the obstacle and cannot accurately detect a direction of the obstacle with respect to the ultrasonic sensor. Since the radar detects the distance to a nearest one of a plurality of objects present within a radar detection zone the object located at one meter from the radar is present in a case where, for example, a detection range limit is one meter.
A characteristic of a detectable range of the radar prescribes as within some meters in a direction orthogonal to a center axis of a detection beam for each detected distance from the center axis or within some degrees from the center axis. For example, it prescribes as within 0.5 meters in the direction orthogonal to the center axis of the detection beam from the center axis or within 26 degrees from the center axis of the detection beam. In this case, the radar has a measurement error for the object one meter ahead by one meter at a maximum in the direction orthogonal to the center axis from the center axis of the detection beam or the measurement error by 52 degrees at the maximum from the center axis of the detection beam.
Since, in each of the previously proposed vehicular obstacle detecting apparatuses described above, such a radar having the spreading detection beam is used, the distance to the nearest point of the obstacle can accurately be detected but the direction of the obstacle cannot accurately be detected. Hence, it is not possible to accurately detect a position of the obstacle.
In addition, when the object (obstacle) is detected by the radar having the spread detection beam, a width of a convex portion of the object is caught to be wider than an actual convex portion thereof. When each convex portion of both ends falls in a detection range of the radar as far as the convex portion is provided on both ends of a recess portion is concerned, the convex portion of both ends is caught to be wider than the actual convex portion so that the recess portion is accordingly caught to be narrower than the actual recess portion. In certain circumstances, the distance to a deepest portion of the recess portion cannot be detected. In other words, each of the previously proposed vehicular surrounding obstacle detecting apparatuses cannot accurately be detect the convex and recess of the object.
Furthermore, since, in each of the previously proposed vehicular surrounding detecting apparatuses, parts of the detection ranges of a plurality of ultrasonic sensors are mutually overlapped, each of the ultrasonic sensors is needed to be operated with a predetermined time margin in order to prevent an interference of detection beams between the sensors and it takes a considerable time to grasp a rough position of the object, i.e., the obstacle.
It is, hence, an object of the present invention to provide apparatus and method for detecting an object present in a surrounding detection zone of an automotive vehicle which can detect a position and a profile of the obstacle present in a surrounding area of the vehicle with a high accuracy and as early as possible.
The above-described object can be achieved by providing a method for detecting a position of an object present in a surrounding detection zone of an automotive vehicle, comprising: measuring a distance of the vehicle to the object; photographing the surrounding detection zone of the vehicle; image processing the photographed surrounding detection zone to extract at least one longitudinal edge from the photographed surrounding detection zone of the vehicle; and detecting the position of the object to the vehicle on the basis of a direction of the extracted longitudinal edge and a measured value of the distance to the object.
The above-described object can also be achieved by providing an apparatus for detecting a position of an object present in a surrounding detection zone of an automotive vehicle, comprising: a distance measurement unit to measure a distance of the vehicle to the object; a photograph device to photograph the surrounding detection zone of the vehicle; an image processing section that performs an image processing for the photographed surrounding detection zone to extract at least one longitudinal edge from the photographed surrounding detection zone image; and a position detecting section that detects the position of the object to the vehicle on the basis of a direction of the extracted longitudinal edge and a measured value of the distance to the object.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.